# https://www.facebook.com/prayash.mohapatra.376/posts/391656181833378
# Subscribed by Code House
# Program to check palindrome string
import java.util.Stack;
import java.util.Scanner;
class PalindromeTest {
public static void main(String[] args) {
System.out.print("Enter any string:");
Scanner in=new Scanner(System.in);
String inputString = in.nextLine();
Stack stack = new Stack();
for (int i = 0; i < inputString.length(); i++) {
stack.push(inputString.charAt(i));
}
String reverseString = "";
while (!stack.isEmpty()) {
reverseString = reverseString+stack.pop();
}
if (inputString.equals(reverseString))
System.out.println("The input String is a palindrome.");
else
System.out.println("The input String is not a palindrome.");
}
}
Input: " 3+5 / 2 "
Output: 5
Note:
You may assume that the given expression is always valid.
Do not use the eval built-in library function.
先保存数字，再保存运算符
import java.util.Stack;
class Solution {
public static int calculate(String s) {
char[] chars = s.replace(" ", "").toCharArray();
long res = 0, num = 0;
char op = '+';
Stack<Long> st = new Stack();
for (int i = 0; i < chars.length; i++) {
if (chars[i] >= '0')
num = num * 10 + chars[i] - '0';
if (chars[i] < '0' || i == chars.length - 1) {
//switch case
if (op == '+')
st.push(num);
else if (op == '-')
st.push(-num);
else if (op == '*' || op == '/') {
Long tmp = (op == '*') ? st.pop() * num : st.pop() / num;
st.push(tmp);
}
op = chars[i];
num = 0;
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from java.util import Stack
a = Stack()
for k in range(10):
a.push(k)
print(a.search(7))
print(a.peek())
print(a.pop())
print(type(a))
print(a)
